>> president obama called the bombings an act of terror. >> this was a heinous and cowardly act, and given what we now know about what took place, the fbi's investigating it as an ability of terrorism. any time bombs are used to target innocent civilians, it is an ability ct of terror. >> new details about the horrif horrific act. here's what we know at the moment. the number of people killed stands at three. that includes an 8-year-old boy. >> police have just raised the number of people wounded. they now say 176 people were hurt in the blast, at least 17 are in critical condition but still no arrests and no group has claimed responsibility for the attack. >> the fbi leading the investigation, authorities say they are following several leads. you are looking here at live pictures. we've got live pictures. there are of the crime scene, overlooking copley square in boston. >> investigators are combing through every inch. they are simply searching for clues, anything to bring attention to this. we've got an update on the investigation. this news conference happened just a short time ag